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--- implementation_unwrap_modulo [2018/09/19 16:45]
supergnu
+++ implementation_unwrap_modulo [2018/09/19 17:11] (current)
supergnu
@@ Line 1: / Line 1: @@
-====== C implementation of a modulo function ======
+====== C implementation of the Octave/Matlab unwrap function ======
+The unwrap function in Octave/Matlab is simplifying the modulo of an arrray.
 It's an easy piece of code but handy to have it around off the shelf:
-<code C modulo.c>
+<code C unwrap.c>
-int modulo(int *values, int numberOfValues, int modulo)
+int unwrap(int *values, int numberOfValues, int modulo)//modulo = 360
 {
-    for (int i = 0; i < numberOfValues; i++)
+    int add = 0;
+    for (int i = 1; i < numberOfValues; i++)
     {
-        while(values[i] > modulo/2 || values[i] < modulo/2)
+        while(abs(values[i-1] - values[i])  > modulo/2)
         {
-            (values[i] > modulo/2) ? values[i] -= modulo : values[i] += modulo;
+            (values[i-1] > values[i]) ? add += modulo : add -= modulo; //could be faster if i kept the phase between samples
-        }
+            values[i] += add;                                          // but longer and less easy to read, in case of perfomance
+        }                                                              // issue, there's probably a way to scrape a few cycles here
+        add = 0;
     }
 }
 </code>

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